This invention relates to methods of casting input/output columns (I/O columns) on the input/output pads (I/O pads) of an electronic component; and more particularly, this invention provides an improved method of casting I/O columns on the I/O pads of an electronic component which enhances yield by greatly reducing breakage of the I/O columns as they are removed from a casting template.
In the prior art, one method for casting I/O columns on the I/O pads of an electronic component is described in U.S. Pat. No. 5,454,159 which is assigned to the assignee of the present invention. There, a process for casting I/O columns on the I/O pads 21 of an electronic component 20 is shown in FIGS. 1-7. Typically, the electronic component 20 is an integrated circuit package which holds one or more integrated circuit chips.
All of the I/O columns in patent '159 are cast the by using a template 40 which that patent shows in FIG. 5. This template 40 has a set of alignment holes which are indicated by reference numerals 41a and 41b, and it has a set of casting holes which are indicated by reference numeral 42. The alignment holes 41a and 41b are used to hold the template 40 at a particular position in a fixture 10, and the casting holes 42 are used to cast the columns on the I/O pads of the electronic component.
In patent '159, the casting step is shown in FIGS. 6 and 7. Then, the I/O columns are removed from the template in a conventional fashion by grasping the electronic component on one pair of edges, grasping the template on another pair of edges, and pulling them apart. However, such pulling must be done with extreme care because the I/O columns are microscopic in size and thus they can easily break.
Typically, the total number of I/O columns on a single electronic component is over four hundred. If a single one of those columns breaks, then the component must be scraped; or, all of the I/O columns must be stripped from the component and the entire casting process must be repeated.
In a mass production environment, the above problem will be catastrophic if it occurs too frequently. This is because all of the components that are scraped or reworked add to the overall cost of manufacturing the products that actually get shipped to a customer. If that overall cost gets too high, the product will fail in the market place.
Accordingly, a primary object of the present invention is to provide an improved method of casting I/O columns on the I/O pads of an electronic component which enhances yield by avoiding the above problem.